He shot Ms Phillips once in the head upstairs and then opened fire on Garda Golden.

Garda Golden would never know that his last actions before entering number 16 Mullach Alainn in Omeath would actually save the life of another man.

Sean Phillips was not injured in the attack as he remained outside the house and he alerted emergency services to the horror.

Statement

Mr Phillips had encouraged his daughter to make the domestic assault complaint about Mackin and joined her as she went to Omeath Garda Station on Sunday evening to make a statement following up on this.

Savage Adrian Crevan Mackin had a long history of brutally assaulting and threatening his 21-year-old partner, it emerged last night.

His relationship with the young mother he shot in cold blood had become increasingly fractured in recent times, and it was known locally that she feared Mackin and was often worried about her safety.

The final savage attack by Crevan Mackin on the young woman happened on Saturday at their home in Mullach Alainn estate, Omeath.

Sources have revealed that after this incident, she contacted local gardai on Saturday by phone after being persuaded to do so by her dad. Gardai then arranged an appointment for her to visit the station to make a voluntary statement of complaint on Sunday afternoon.

In that statement, it is understood that Ms Phillips said she was assaulted on Saturday but also gave additional information about previous beatings and threats which she had endured from Crevan Mackin during the course of their relationship.

"The way that IRA thug treated that woman over a considerable period of time was absolutely shocking," a source said last night.

After his partner provided a statement in Omeath Garda Station, Garda Golden went with Ms Phillips and her father to the house so that she could retrieve some personal belongings.

Supt Gerry Curley explained that after hearing the gunshots that critically wounded Siobhan and killed Garda Golden, her father raised the alarm.

"On entering the house garda Tony Golden was found with a number of gunshot wounds which proved to be fatal. Another male, who has now been identified as Adrian Crevan Mackin, was found with a fatal gunshot wound," he said.

Siobhan Phillips - the mother of two children - remains in critical condition in Beaumont Hospital.

Last night, it also emerged that a Polish man who was renting a room in the murder house has given gardai a statement but it's not known what exactly he witnessed.

Shock

Yesterday, Garda Commissioner Noirin O'Sullivan visited the family of Garda Golden and afterwards said there were no words to describe the shock and grief.

"Obviously all of the members (of the Gardai) are very shocked and very hurt and very saddened by everything that has happened and we are here to support them (the family)," the Commissioner added.

Prior to Sunday's shooting the Garda Representative's Association called for gardai to be better protected and for "a serious debate into the introduction of tasers" to be had.

Garda Golden will be remembered at a special mass in Dundalk Garda Station at 11am this morning and will be laid to rest on Thursday following a State funeral.